1. Field of the Invention
The invention relates to a power control system, more particularly to a feedback power control system for an electrical component.
2. Description of the Related Art
FIG. 1 illustrates the relationship between an emitted power and a work current of a light emitting diode at different temperatures. In FIG. 1, the emitted power of the light emitting diode decreases with an increase in the temperature of the light emitting diode. Thus, it is required to stabilize the unstable consumed power of the light emitting diode.
In order to stabilize an emitted power of a light emitting diode, a conventional power control circuit 10 has been proposed as shown in FIG. 2. The conventional power control circuit 10 for a light emitting diode 15 includes a photodetector 14 for detecting an emitted power of the light emitting diode 15, and a driving unit 16 for providing a voltage signal or a current signal to the light emitting diode 15 based on the detecting result from the photodetector 14.
However, due to the poor directionality of light emitted by the light emitting diode 15, the detection result is affected by a distance between the photodetector 14 and the light emitting diode 15, the ambient brightness, and sensitivity of the photodetector 14. Furthermore, the photodetector 14 is used to detect the light emitting diode 15 emitting light having a specific wavelength. As a result, the conventional power control circuit 10 cannot ensure stable power control for different light emitting diodes 15.